Process for the alkylation of aromatic compounds

ABSTRACT

Process for preparing alkylated aromatic compounds which comprises reacting an aromatic compound with a ketone and hydrogen in the presence of a catalytic composition comprising a solid acid material and copper. A preferred aspect is to use a catalytic composition also containing one or more elements selected from elements of groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and of the series of lanthanides. A particularly preferred aspect is to use a catalytic composition containing one or more elements selected from elements of groups IIIA and VIB.

The present invention relates to a process for the alkylation ofaromatic compounds which comprises reacting an aromatic compound with aketone and hydrogen in the presence of a catalytic compositioncomprising a solid acid material and copper. A preferred aspect is forthe catalytic composition to also contain one or more elements selectedfrom elements of groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIIIlimited to Fe, Ru and Os, and of the series of lanthanides. Aparticularly preferred aspect is for the catalytic composition tocontain one or more elements selected from elements of groups IIIA andVIB.

In particular, the invention relates to a process for the production ofcumene starting from the reagents acetone, benzene and hydrogen, whichare reacted in a single reaction step in the presence of said catalyticsystem.

Even more specifically, the invention relates to an alkylation processof an aromatic hydrocarbon, preferably benzene, with acetone andhydrogen in the presence of a catalytic composition containing a solidacid material, copper and one or more elements selected from Cr and Al,wherein the solid acid material comprises or consists of a zeolite,preferably zeolite beta.

The new preparation of cumene according to the present invention can beused in particular in a production process of phenol comprising thefollowing steps:

-   (a) reacting benzene, acetone and hydrogen in the presence of the    catalytic system according to what is specified above, comprising a    solid acid material and copper,-   (b) oxidizing the cumene to cumene hydroperoxide,-   (c) treating the cumene hydroperoxide with acids to obtain a    re-arrangement to phenol and acetone.

A preferred aspect is for the catalytic composition used in step (a) toalso contain one or more elements selected from elements of groups IIIA,IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, andof the series of lanthanides. A particularly preferred aspect is for thecatalytic composition of step (a) to contain one or more elementsselected from elements of groups IIIA and VIB.

The acetone which is formed in step (c) can be recycled to step (a) forthe synthesis of cumene.

According to what is specified above, the catalytic composition used instep (a) preferably comprises zeolite beta and copper. A particularlypreferred aspect is to use in step (a) a catalytic compositioncontaining zeolite beta, Cu and a metal selected from Cr and Al.

Cumene or isopropyl benzene is an important intermediate in the basicchemical industry mainly used as precursor for the production of phenol,in turn useful as intermediate in the preparation of caprolactam fromwhich nylon is produced.

The industrial synthesis of phenol comprises the alkylation steps ofbenzene to cumene, the oxidation of cumene to cumyl hydroperoxide andthe subsequent rearrangement to give phenol and acetone.

As far as the alkylation of benzene to cumene is concerned, catalystsbased on phosphoric acid and infusorial earth for fixed bed reactors orAlCl₃ in slurry, and propylene as alkylating agent, are still widelyused in the petrochemical industry.

These processes however create problems relating to environmental impactand safety: the use of these catalysts, in fact, is particularlyproblematical due to corrosion, the by-production of toxic organicproducts and the disposal of the exhausted catalysts.

In 1965, however, the preparation of cumene was described for the firsttime, using zeolite X or zeolite Y as catalyst (Minachev, Kr. M., et al,Neftekhimiya 5 (1965) 676). The use of zeolites with a faujasiticstructure for the alkylation of benzene with light olefins such aspropylene, was subsequently described by Venuto et al. (J. Catal. 5,(1966) 81).

U.S. Pat. No. 4,292,457 describes the use of ZSM-5 type zeolites foralkylating benzene with propylene.

Excellent results in terms of industrial application have been obtainedin the synthesis of cumene using zeolites with a beta-type structure, asdescribed in EP 432814, and in particular using catalysts comprisingzeolite beta according to what is described in EP 687500 and in EP847802.

Once cumene has been obtained, it is transformed into phenol by means ofan oxidation step to cumene hydroperoxide, followed by an acid treatmentstep which causes the breakage of the peroxide bond with the formationof phenol and acetone.

The synthesis of phenol via cumene, on which most industrial plantsexisting throughout the world for the production of phenol, are based,leads to the co-production of a quantity of acetone equal to 0.61 kg perkg of phenol.

Phenol is mainly used in the production of bisphenol A (about 35%),phenolic resins (about 35%), caprolactam (about 15%), aniline,alkylphenols, xylenols and other products, whereas acetone is mainlyused in the production of methylmethacrylate (about 45%), bisphenol A(about 20%), solvents (about 17%) and methylisobutylketone (about 8%).

There is therefore an unbalanced situation, at least potential, in therequest for phenol and acetone, intrinsically deriving from theirco-production, which does not allow a modulation in their supply inrelation to the growth margins of the different sectors and outletmarkets for the two products.

New processes based on the re-use of acetone—co-produced with phenol—inthe upstream synthesis of cumene, have been proposed to avoid thissituation. In EP 361755, the propylene used as alkylation agent ofbenzene for the synthesis of cumene is obtained, either totally orpartially, starting from acetone, after reduction with hydrogen toisopropanol and subsequent dehydration to propylene.

The re-use of the possible excess acetone for the re-production ofpropylene according to the method described above, is extremely onerous,particularly due to the high number of steps associated with thechemical reduction transformations to isopropyl alcohol and thesubsequent dehydration of the alcohol to propylene.

An alternative which reduces the number of chemical transformationsnecessary for the re-use of acetone consists in the direct use ofisopropanol, obtained by the reduction of acetone with hydrogen, asalkylation agent of benzene in the synthesis of cumene, as described forexample in EP 1069100.

The direct alkylation of benzene with isopropanol, obtained by thereduction of acetone co-produced with phenol, represents an improvement,from an industrial point of view, with respect to the option whichinvolves the re-production of propylene to be used as alkylation agentof benzene, but the best solution, from an industrial and process pointof view, would obviously consist of the direct use of acetone asalkylation agent of benzene, in the presence of hydrogen, in thesynthesis of cumene.

A catalytic system has now been found, which is capable of promoting thesynthesis of cumene starting directly from the reagents acetone, benzeneand hydrogen.

The cumene, obtained according to the industrial process claimed herein,can be used for the subsequent production of phenol by means ofoxidation to cumene hydroperoxide and the subsequent rearrangement ofthe hydroperoxide to phenol and acetone. The acetone thus obtained, canin turn be used for the synthesis of cumene by the direct alkylation ofbenzene with acetone and hydrogen carried out according to theindustrial process claimed herein.

The object of the present invention therefore relates to a process forthe alkylation of aromatic compounds which comprises reacting anaromatic compound with a ketone and hydrogen in the presence of acatalytic composition comprising a solid acid material and copper. Apreferred aspect is for the catalytic composition to also additionallycontain one or more elements selected from elements of groups IIIA, IVA,IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and ofthe series of lanthanides. A particularly preferred aspect is for thecatalytic composition to contain one or more elements selected fromelements of groups IIIA and VIB. The aromatic compound is preferablybenzene.

The ketone is preferably acetone.

More specifically, the object of the present invention relates to aprocess for the alkylation of benzene to give cumene which comprisesreacting acetone, benzene and hydrogen, which are reacted in a singlereaction step, in the presence of a catalytic system comprising a solidacid material and copper. A preferred aspect is for the catalyticcomposition used for the alkylation of benzene to cumene to additionallycontain one or more elements selected from elements of groups IIIA, IVA,IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and ofthe series of lanthanides. A particularly preferred aspect is for thecatalytic composition to contain one or more elements selected fromelements of groups IIIA and VIB, preferably Cr or Al.

The alkylation process, object of the present invention, allows thepreparation of phenol from cumene to be considerably simplified; it isnot necessary in fact to first effect the chemical reductiontransformation of acetone to isopropanol as described for example inU.S. Pat. No. 5,160,497, the subsequent chemical dehydrationtransformation of isopropanol to propylene as described for example inU.S. Pat. No. 5,017,729 and consequently the subsequent chemicalalkylation transformation of benzene with propylene as described forexample in EP 439632.

The chemical transformations described above are normally carried outunder somewhat different reaction conditions for each of the reactionsin question and in the presence of equally different catalysts.

The catalytic system used in the process of the present invention allowsall the chemical transformations necessary for the preparation of cumenestarting from the reagents acetone, benzene and hydrogen, to becontemporaneously carried out in a single reaction step, maximizing theyield to cumene and minimizing the secondary reactions of the variousreagents, intermediates and products.

Particularly significant secondary and undesired reactions fordetermining the overall yield which could be expected by experts in thefield are the parallel reduction reaction of benzene with hydrogen tocyclohexene, cyclohexane and hexane, the parallel condensation reactionof acetone to 4-methyl-3-penten-2-one and the subsequent reactions ofthese by-products with the various reagents and products of the mainreactions such as for example the alkylation of benzene tophenylcyclohexane due to the cyclohexene and reduction of4-methyl-3-penten-2-one to 4-methyl-2-pentanone and 4-methyl-2-pentanoldue to the hydrogen.

The catalytic system used in the process of the present inventionunexpectedly allows the conversion of the reagents to be orientedtowards the desired product, reducing the formation of undesiredproducts to the minimum.

The catalytic system used in the alkylation process of aromaticcompounds, in particular benzene, which is object of the presentinvention, comprises a solid acid material and copper, wherein thecopper is preferably in the form of an oxide.

According to a preferred aspect, the catalytic composition also containsone or more elements selected from elements of groups IIIA, IVA, IIIB,IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and of theseries of lanthanides. These elements of groups IIIA, IVA, IIIB, IVB,VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and of the series oflanthanides, are also preferably in the form of oxides. In particular,copper and these elements can be contained in the catalytic compositionin the form of a mixed oxide.

According to a particularly preferred aspect, the catalytic compositioncontains one or more elements selected from the elements of groups IIIAand VIB. In accordance with what is specified above, these elements ofgroups IIIA and VIB are preferably in the form of oxides. In particular,copper and these elements can be contained in the catalytic compositionin the form of a mixed oxide.

A particularly preferred aspect of the present invention is to usecatalytic compositions containing copper and an element selected fromchromium and aluminum. In particular, copper and these elements can becontained in the catalytic composition in the form of a mixed oxide.

In particular, copper and chromium can be contained in the catalyticcomposition in the form of copper chromite. Copper chromite isrepresented by the empirical formula CuO—CuCr₂O₄. CuCr₂O₄ is known asC.A.S. R.N. 12018-10-9 and is described in “Gmelins Handbuch derAnorganischen Chemie, 8^(th) ed., Vol. Kupfer, part B, Installment 3,system number 60, page 60”. In the process of the present invention,commercially available materials called copper chromite, can be used,containing Cu (II) and Cr (III), having varying proportions of CuO andCuCr₂O₄. These materials, which can optionally also contain smallquantities of promoters such as Ba and Mn, are well known to experts inthe field and are described for example in J. D. Stoupe, “An X-RayDiffraction Study of the Copper Chromites and of the “Copper-ChromiumOxide” Catalyst” J. Am. Che. Soc., vol. 71, 1949, page 589; in A. Iimuraet al., “Catalysis by “Copper Chromite”, I, The effect of hydrogenReduction on the composition, structure and catalytic activity formethanol decomposition”, Bull. Chem. Soc. Jp., 56, 2203-2207 (1983); inR.B.C. Pillai, “A study of the pre-activation of a copper chromitecatalyst”, Catalysis Letters 26 (1994) 365-371.

Copper and aluminum can be contained in the catalytic composition usedin the present invention in the form of the corresponding oxides.

In accordance with what is specified above, the catalytic compositioncontaining copper chromite can contain, as promoters, barium and/ormanganese, preferably in the form of oxides. The barium or manganesecontent is lower than 15% by weight with respect to the total weight ofthe composition and preferably ranges from 0.1 to 5% by weight. Theweight percentages of barium and manganese refer to their contentexpressed as element.

The solid acid material contained in the catalytic composition used inthe alkylation process of aromatic compounds of the present invention,in particular benzene, is preferably of a zeolitic nature and cancontain one or more zeolitic materials. Zeolites which can be used arezeolite beta, zeolite Y, ZSM-12 and mordenite. These zeolites aredescribed in “Atlas of zeolite structure types”, Ch. Baerolocher, W. M.Meier and D. H. Olson, 2001, 5^(th) Edition, Elsevier. A preferredaspect is to use zeolite beta.

The zeolites are used in acid form, i.e. in the form in which all thenegative charges deriving from the aluminum present in the structure arecounterbalanced by hydrogen ions, or prevalently acid.

The zeolite beta used as component of the catalytic composition of theprocess according to the present invention corresponds to that describedin U.S. Pat. No. 3,308,069, and is a porous crystalline material havingthe composition[(x/n)M(1±0.1−x)TEA]AlO₂ .ySiO₂ .wH₂Owherein n is the oxidation state of M, x is less than 1, y ranges from 5to 100, w ranges from 0 to 4, M is a metal selected from those of groupsIA, IIA, IIIA of the Periodic System or from transition metals and TEAis tetraethyl ammonium hydroxide.

A preferred aspect of the present invention is for the zeolite beta tobe in acid form, i.e. in the form in which the H⁺ ion has partially ortotally substituted the metallic cations initially present.

This substitution is effected according to the known methods by means ofan exchange with ammonium ions, washing and subsequent calcination.

The catalytic compositions which can be used in the alkylation processof the present invention, comprising a solid acid material and copper,can comprise suitable binding agents, for example oxides of groups IIIA,IVA and IVB. More preferably, the catalytic system can contain an oxideof Si or Al as binding carrier. Even more preferably, the catalyticsystem can contain γ-alumina as binding carrier.

γ-alumina is a known material and is commercially available in the form,preferred for the purposes of the invention, of the precursors bohemiteor p-bohemite, transformed subsequently to γ-alumina during thepreparation of the catalytic system, in the final calcination phase.

The binder is preferably used in a relative quantity by weight withrespect to the catalytic system ranging from 5:95 to 95:5.

A particularly preferred aspect of the present invention is to use acatalytic system containing copper chromite and a beta-type zeolite, inits acid form. This composition can contain an inorganic binder inaccordance with what is described above.

The copper is preferably contained in the catalytic composition of thepresent invention in a weight ratio of the metal with respect to thesolid acid material ranging from 0.001 to 10, more preferably rangingfrom 0.01 to 2. When the catalytic composition contains one or moreelements of groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIIIlimited to Fe, Ru and Os, and of the series of lanthanides, each elementis preferably contained in a weight ratio of the metal with respect tothe solid acid material ranging from 0.001 to 10, more preferably from0.01 to 2.

The catalytic system used in the present invention, as described above,contains a solid acid component with an alkylation functionality and ametallic component containing copper and optionally one or more elementsselected from elements of groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB,group VIII limited to Fe, Ru and Os, and of the series of lanthanides,with a hydrogenation functionality.

The catalytic system used in the present invention, containing a solidacid component and a metallic component containing copper and optionallyone or more elements selected from elements of groups IIIA, IVA, IIIB,IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and of theseries of lanthanides, can be prepared, starting from the componentsdescribed above, according to various practical combination procedures,each maintaining the specific characteristics listed above.

The catalytic system of the present invention can therefore consist ofone or more distinct zones each containing a single functionality,either hydrogenation linked to the metallic component or alkylationlinked to the acid component, in particular zeolitic, or bothhydrogenation and alkylation functionalities having the characteristicsdescribed above.

Examples of some of the various preparation procedures of the catalyticsystem are indicated below and are schematically represented in FIG. 1.

In this figure, I refers to the metallic component of the catalyticcomposition, containing copper and optionally one or more elementsselected from elements of groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB,group VIII limited to Fe, Ru and Os, and of the series of lanthanides,said component having a hydrogenation functionality. When the metalliccomponent contains copper alone, this is preferably in the form of anoxide. When the metallic component also contains an element selectedfrom groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited toFe, Ru and Os, and of the series of lanthanides, it is also preferablyin the form of an oxide. In this case, the component can be prepared forexample by the mechanical mixing of the oxides. In the particular casein which the copper and the element or elements selected from groupsIIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru andOs, are in the form of a mixed oxide, component I can be prepared forexample according to the known coprecipitation techniques, or by meltingthe metal oxides present in the mixed oxide. The metallic component Ipreferably consists of copper chromite.

Again with reference to FIG. 1, A refers to the solid acid component,preferably zeolitic, containing the alkylation functionality. Zeoliteswhich can be used are preferably zeolite beta, zeolite Y, ZSM-12 andmordenite. A preferred aspect is to use zeolite beta. The solid acidcomponent, preferably zeolitic, can be used in a mixture with suitablebinding agents, for example oxides of the elements of groups IIIA, IVAand IVB. The solid acid component A more preferably contains an oxide ofSi or Al as binding carrier. Even more preferably, the solid acidcomponent A contains γ-alumina as binding carrier. The zeoliticcomposition with binder can be prepared according to any of the knowntechniques. In the case of zeolite beta, it can be prepared, forexample, as described in EP 687500 and EP 847802.

Again with reference to FIG. 1, AI refers to a composition containingboth hydrogenation and alkylation functionalities. The compositionindicated with AI can also comprise suitable binding agents, for exampleoxides of groups IIIA, IVA and IVB. The composition indicated with AImore preferably contains an oxide of Si or Al as binding carrier. Evenmore preferably, the composition AI contains γ-alumina as bindingcarrier. The composition AI can be prepared according to any of thetechniques well known to experts in the field, such as for example a)impregnation, b) ion exchange or c) extrusion, described hereunder:

-   a) it is possible to operate for example by impregnating the solid    acid material, preferably of a zeolitic nature, with an aqueous    solution containing a copper salt and optionally a salt of an    element selected from groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB,    group VIII limited to Fe, Ru and Os, and of the series of    lanthanides, drying and calcining the resulting product. Separate    solutions for the copper salt and salt of the element of groups    IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru    and Os, and of the series of lanthanides, can be used. The product    obtained with this method can be optionally used in a mixture with a    suitable binding agents, for examples oxides of groups IIIA, IVA and    IVB, as described above. Alternatively, it is possible to operate by    impregnating a mixture of solid acid material and binding agent with    an aqueous solution containing a copper salt and optionally a salt    selected from groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII    limited to Fe, Ru and Os, and of the series of lanthanides, drying    and calcining the resulting product.-   b) When the ion exchange technique is used, the solid acid material,    preferably of a zeolitic nature, is for example put in an aqueous    solution containing a copper salt and optionally a salt selected    from groups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited    to Fe, Ru and Os, and of the series of lanthanides, and the mixture    left under stirring for a few hours. The solid in suspension is    recovered by filtration, washed with demineralized water and dried:    a solid acid material is obtained in exchanged form with copper ions    and possibly ions of a metal selected from groups IIIA, IVA, IIIB,    IVB, VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and of the    series of lanthanides. The material obtained in this way can    optionally be used in a mixture with a suitable binding agent, as    defined above. Alternatively, a composition of a solid acid material    and of suitable binding agents is used, which is subjected to the    ion exchange process described above.-   c) Alternatively, an extrusion process can be used, in which a    mechanical mixture of the two components, i.e. the solid acid    material, preferably zeolitic, and the metallic component, is    paste-mixed with a peptizing acid solution, extruded, dried and    calcined with any traditional method. The product obtained in this    way can optionally be used in a mixture with a suitable binding    agent, defined above. Alternatively, a mechanical mixture of the    three components, i.e. the solid acid material, preferably zeolitic,    the metallic component and a suitable binding agent, defined above,    is subjected to an extrusion process. In accordance with what is    specified above, the catalytic system can consist for example (FIG.    1 a) of a sole AI composition zone containing both metallic and acid    components, having alkylation and hydrogenation functionalities.

According to another embodiment, the catalytic system can consist forexample (FIG. 1 b) of two or more separate AI composition zones, each ofwhich contain both the acid and metallic components, having alkylationand hydrogenation functionalities, wherein the composition of the singlezones differs in terms of chemical nature and proportion between thealkylation and hydrogenation functionality. Each single zone of the AIcomposition is prepared with one of the known methods described above,and the zones are then assembled by stratification inside the reactor.

Another preparation procedure (FIG. 1 c) of the catalytic systemconsists for example of two or more distinct zones, in one of whichthere is the metallic component I containing the catalytic hydrogenationfunction alone, whereas in the remaining zones there are one or morecompositions AI with different combinations of the two components havingalkylation and hydrogenation functionalities. Each single zone of thecomposition AI, containing two functionalities, is prepared with one ofthe known methods described above.

In another embodiment (FIG. 1 d), the catalytic system consists forexample of two or more distinct zones, in one of which there iscomponent I containing the catalytic hydrogenation function alone,whereas in the subsequent zone there is component A, having analkylation catalytic function. The acid component A, preferablyzeolitic, can be used in a mixture with suitable binding agents, definedabove.

In a further embodiment (FIG. 1 e) the catalytic system consists forexample of a single zone in which the two components of the catalyticcomposition, I and A respectively, mechanically mixed with each other,are arranged. Also in this case, the solid acid component A, preferablyzeolitic, can be used in a mixture with suitable binding agents definedabove.

In yet another embodiment (FIG. 1 f), the catalytic system consists forexample of two or more distinct zones, in one of which there iscomponent I of the catalytic system containing the catalytichydrogenation function alone whereas in the remaining zones there areone or more different pairs of components I and A, mechanically mixed,each of which contains the catalytic hydrogenation function alone or thecatalytic alkylation function alone. Also in this case, the solid acidcomponent, preferably zeolitic, can be used in a mixture with suitablebinding agents defined above.

When the catalytic system has a zone containing the metallic component Ialone, having a catalytic hydrogenating function, this is preferably theone which first comes into contact with the stream of reagents, inparticular benzene, acetone and hydrogen. Furthermore, it is evidentthat, on the basis of the procedures described, a catalytic systemcharacterized by the contemporaneous presence of a hydrogenationfunction, whose activity gradient decreases in one direction, and analkylation function, whose activity gradient decreases in the oppositedirection, can be easily produced by experts in the field, if desired.

The activity gradient of the hydrogenation function preferably decreasesalong the feeding direction and flow of the reagents, in particularacetone, benzene and hydrogen, whereas the activity gradient of thealkylation function decreases along the opposite direction and flow.

According to a preferred aspect of the alkylation process of the presentinvention, it is preferable to operate at a reaction temperaturegenerally ranging from 50 to 350° C., preferably from 100 to 250° C. Thepressure is generally equal to or higher than atmospheric pressure andpreferably ranges from 1 to 50 bars. A molar ratio between aromatichydrocarbon and ketone, in particular between benzene and acetone, isused in the feeding, not lower than 1 and preferably higher than 2. Amolar ratio between hydrogen and ketone, in particular acetone, is usedin the feeding not lower than 1 and preferably higher than 2. Thecatalytic composition is preferably pre-activated in a stream ofhydrogen.

The reaction can be conveniently carried out in fixed bed catalystreactors, containing one or more catalytic beds. The reagents can inthis case all be fed to the reactor, in the desired proportions, to thefirst catalytic bed, or the feeding of the reagents or some of them canbe partially fed to the different catalytic beds.

Some of the compositions prepared with the methods described abovehowever can also be conveniently used in reactors different from fixedbed reactors.

According to the process claimed herein and according to an embodimentof the invention, with reference to FIG. 2, benzene, acetone andhydrogen are reacted in a single step in the presence of the catalyticsystem described and under the conditions indicated for obtaining areaction product which mainly contains isopropylbenzene, non-convertedbenzene, non-converted hydrogen, water and polyisopropylbenzenes.

The reaction product is fractionated in a separation section S usingconventional separation methods, such as degassing, distillation or thedemixing of liquids, to obtain a first fraction mainly containinghydrogen, a second fraction mainly containing water, a third fractionmainly containing benzene, a fourth fraction mainly containingisopropylbenzene and a fifth fraction mainly containingpolyisopropylbenzenes.

The first fraction (containing hydrogen) is re-used in the reaction stepwith acetone and benzene, the second fraction (containing water) isremoved from the process, the third fraction (containing benzene) ispartly re-used in the reaction step with acetone and hydrogen and partlyin a subsequent reaction step, called transalkylation step, where it isreacted with the fifth fraction (containing polyisopropylbenzenes) toproduce again the desired product isopropylbenzene.

Transalkylation is a reaction which is well known in the state of theart and is carried out in the presence of a solid acid catalyst,preferably in the presence of a solid acid catalyst based on zeolites,more preferably in the presence of a solid acid catalyst based onbeta-type zeolite as described for example in EP 687500 and in EP847802.

The temperature conditions for the transalkylation reaction are selectedfrom 100 to 350° C., the pressure is selected from 10 to 50 atm and theWHSV ranges from 0.1 to 200 hours⁻¹, as also described in EP 687500 andin EP 847802.

The transalkylation reaction product is fractionated using theconventional separation methods in the same separation section.

The third fraction coming from the separation section therefore containsnon-converted benzene coming from both the alkylation step and thetransalkylation step. The fourth fraction coming from the separationsection contains cumene coming from both the alkylation step and thetransalkylation step and the fifth fraction coming from the separationstep contains polyisopropylbenzenes coming from both the alkylation stepand the transalkylation step.

The cumene obtained according to the process, object of the presentinvention, can be used for the production of phenol by means ofoxidation to cumene hydroperoxide and the subsequent rearrangement ofthe hydroperoxide to phenol and acetone.

A further object of the present invention therefore relates to a processfor the production of phenol which comprises the following steps:

-   (a) reacting benzene, acetone and hydrogen in the presence of a    catalytic system comprising a solid acid material and copper-   (b) oxidation of cumene to cumene hydroperoxide-   (c) rearrangement of the cumene hydroperoxide to phenol and acetone.

The acetone which is formed in step (c) can be recycled to the synthesisstep (a) of cumene.

The catalytic composition used in step (a) also preferably contains oneor more elements selected from elements of groups IIIA, IVA, IIIB, IVB,VB, VIB, VIIB, group VIII limited to Fe, Ru and Os, and of the series oflanthanides, and is in accordance with what is specified above withrespect to the alkylation process of the present invention. Thecatalytic composition used preferably contains zeolite beta, copperchromite and optionally an inorganic binder.

The various passages for the oxidation of cumene to cumenehydroperoxide, the rearrangement of hydroperoxide to give phenol andacetone and the purification of phenol are well known in literature, asdescribed for example in U.S. Pat. Nos. 5,160,497 and 5,017,729.

The oxidation step of cumene to cumene hydroperoxide can be carried outfor example with molecular oxygen at a temperature ranging from 60 to150° C. and at a pressure ranging from 1 to 10 kg-f/cm². It ispreferable to operate in the presence of an initiator and an alkalinecompound for the pH control.

The transformation step of cumene hydroperoxide to phenol and acetone iscarried out in the presence of an acid, for example a strong acid suchas sulfuric acid, or for example an exchange resin or a silico-alumina.At the end, the reaction mixture is concentrated to recover the acetone,which can then be recycled to the alkylation step (a). It can be clearlyseen how a process for the production of phenol starting from hydrogen,oxygen and benzene, with the coproduction of water alone, can actuallybe effected by recycling the acetone to step (a).

According to a preferred aspect, at the end of the first step, afterseparating the desired product, cumene, by fractionation, which passesto the subsequent oxidation step, the remaining fraction ofpolyisopropylbenzenes is used in a separate step for a transalkylationreaction with benzene to recover other cumene.

The transalkylation reaction is carried out in the presence of zeolitebeta or a catalyst based on zeolite beta, in particular preparedaccording to what is described in EP 687500 and EP 847802, which alsodescribe the reaction conditions.

The catalytic composition of the present invention containing a zeolitein acid form, preferably zeolite beta, Cu, and optionally one or moreelements selected from elements of groups IIIA, IVA, IIIB, IVB, VB, VIB,VIIB, group VIII limited to Fe, Ru and Os, and of the series oflanthanides, is new and is a further aspect of the present invention.

This catalytic composition preferably contains zeolite beta, Cu and anelement selected from Cr and Al. The metals contained in the compositionare preferably in the form of oxides. According to a particular aspectof the present invention, copper and chromium are contained in the formof copper chromite.

The copper is preferably contained in the catalytic composition of thepresent invention in a weight ratio of the metal with respect to thezeolite ranging from 0.001 to 10, more preferably ranging from 0.01 to2. When the catalytic composition contains one or more elements ofgroups IIIA, IVA, IIIB, IVB, VB, VIB, VIIB, group VIII limited to Fe, Ruand Os, and of the series of lanthanides, each element is preferablycontained in a weight ratio of the metal with respect to the zeoliteranging from 0.001 to 10, more preferably from 0.01 to 2. When themetallic component of the catalytic composition used in this patentcomprises copper chromite, Ba and Mn can be present as promoters. Thesecatalytic compositions may additionally contain a binder. Thepreparation of these catalytic compositions is in accordance with allthe methods previously described.

The following examples are provided for a further illustration of theinvention without limiting its scope in any way.

EXAMPLE 1 Preparation of the Catalytic System

A catalytic system is prepared, consisting of 10 g of a catalyst basedon copper chromite (produced by the company SüdChemie with thetrade-name G99b) having the following composition expressed as weightpercentage of the elements: Cu 35%, Cr 31%, Ba 2%, Mn 2.5%, indicatedhereunder as “material A1” and 4.5 g of a catalyst based on zeolite betaprepared according to the indications described in Example 1 of EP687500, called “material B1”. The zeolite beta used in the preparationof the material B1 is a product of the company Zeolyst with thetradename CP-806 BL 25.

The catalytic system is prepared so that the first zone of said systemconsists of the material A1 alone in a quantity equal to 3 g and thesecond zone consists of a mechanical mixture of materials A1 and B1 in aquantity equal to 7 g of material A1 and 4.5 g of material B1. The totalquantity of the catalytic system thus prepared is therefore equal to14.5 g.

EXAMPLE 2 Preparation of the Catalytic System

A catalytic system is prepared, starting from the materials G-99b (57g)) and zeolite beta (80 g), already used in the previous example, andalumina p-bohemite commercialized by the Company Laroche with thetrade-name Versal 450 (143 g).

The materials are mechanically mixed in a ploughshare mixer for about 25minutes, after which 175 cc of an aqueous solution of acetic acid at 5%w/w are added to the mixture of powders thus obtained, withoutinterrupting the mixing for a further 20 minutes approximately.

The intermediate thus obtained is then subjected to extrusion using aHUTT type gear press extruder and the product thus obtained issubsequently subjected to aging for a time of not less than 48 hours.

After the period of aging, the product, in the form of pellets, is thensubjected to calcination treatment in air at a temperature of 550° C.approx. for 5 hours, obtaining a material called “material B2”,containing about 25% of material G99b, about 30% of zeolite beta andabout 45% of alumina binding carrier.

The catalytic system is prepared so as to consist of a single zone inwhich there is material B2. The total quantity of catalytic system thusprepared is equal to 9.0 g.

EXAMPLE 3 Preparation of the Catalytic System

A catalytic system is prepared, consisting of two distinct zones, thefirst of which contains 3 g of material A1 already used in Example 1 andthe second containing 8 g of material B2 prepared according to theprocedure described in Example 2. The total quantity of catalytic systemis therefore equal to 11 g.

EXAMPLE 4 Preparation of the Catalytic System

37 g of a catalyst based on zeolite beta prepared according to theindications provided in Example 1 of EP 687500 (12-16 mesh), are chargedinto a rotavapor flask having a volume of 500 ml, and are then driedunder vacuum at room temperature for 2 hours.

A solution is prepared, consisting of 30.34 g of demineralized water and8.0 g of copper nitrate, Cu(NO₃)₂.2.5H₂O (MW=232.59, 34.4 mmoles). Thesolid is impregnated at room temperature under vacuum. It is left toslowly rotate, under vacuum for 3 h. It is then dried in an oven for 2 hat 120° C. It is calcined at 316° C./4 h with an increase rate of 1° C.min⁻¹.

A second impregnation, as the previous one but using a solutionconsisting of 4.06 g of Copper nitrate Cu(NO₃)₂.2.5H₂O (MW=232.59, 17.5mmoles) and 15.42 g of demineralized water, is effected on 18.8 g ofproduct, calcined at 316° C.

The solid is impregnated at room temperature under vacuum. It is left toslowly rotate, under vacuum for 3 h. It is dried in an oven for 2 h at120° C. and is calcined at 482° C./8 h with an increase rate of 1° C.min⁻¹.

19.4 g of calcined product are recovered (10.29% Cu).

EXAMPLE 5 Catalytic Test

A catalytic test is carried out, using an experimental apparatus asdescribed below.

The experimental apparatus consists of tanks for the reagents benzeneand acetone, feeding pumps of the reagents benzene and acetone, a massmeter for the flow-rate control of hydrogen coming from a cylinder, astatic mixer of the reagents before their inlet into the reaction, apreheating unit of the reagents, a steel reactor situated inside anelectric heating oven equipped with temperature regulation inside theoven and inside the reactor, a pressure regulation system inside thereactor by means of a pneumatic valve, a cooler of the reaction effluentand a collection system of the liquid and gaseous products.

The reactor, situated inside the heating oven, consists of a steelcylindrical tube, with a mechanical sealing system and internal diameterequal to about 2 cm.

Along the major axis of the reactor there is a thermometer trap having adiameter equal to 1 mm, containing a thermocouple which can run freelyalong the major axis of the reactor and consequently along the majoraxis of the catalytic bed.

The catalytic system prepared as described in Example 1 is charged intothe reactor, in a quantity equal to 14.5 g, with a size ranging from 1to 2 mm, for a total height of the catalytic bed equal to 8.5 cm.

A quantity of inert quartz material is charged over and under thecatalytic bed for a height equal to 2 cm over and 2 cm under thecatalytic bed.

The catalyst is then subjected to drying in a stream of nitrogen at atemperature inside the reactor equal to 160° C. for about 1 hour, and astream of 5.2 ml/min of low pressure hydrogen is subsequently fed for 60minutes, followed by a stream of 15.8 ml/min at 180° C. for 120 minutesand finally a stream of 23.6 ml/min at 200° C. for 180 minutes, afterwhich the hydrogen feeding is interrupted and the temperature of thereactor is brought back to a value equal to 150° C., the experimentalapparatus being continuously maintained in a stream of nitrogen.

Once a constant temperature of 150° C. has been reached, the stream ofnitrogen is then interrupted and the feeding of benzene is initiatedwith a flow-rate equal to 0.245 ml/min.

The system is maintained under these conditions for 60 minutes, afterwhich the feeding of hydrogen is reactivated at a flow-rate equal to27.3 ml/min and after a few minutes the feeding of acetone is initiatedwith a flow-rate equal to 0.012 ml/min.

Approximately 3 hours after the feeding of acetone, samples of reactioneffluent are removed, both for the liquid and gaseous part, which aresubsequently analyzed by gaschromatography.

Table 1 summarizes the operating conditions, together with the resultsobtained. In this table:

-   -   WHSV expresses the ratio between the sum of the hourly        flow-rates of benzene and acetone (excluding hydrogen) and the        quantity of catalytic system;    -   the selectivity [aryls]/[acetone] expresses the fraction of        acetone converted to cumene+polyisopropylbenzenes (products        useful for the production of cumene in transalkylation) with        respect to the total quantity of converted acetone;    -   the selectivity [cumene]/[acetone] expresses the fraction of        acetone converted to cumene with respect to the total quantity        of converted acetone;    -   the selectivity [aryls]/[benzene] expresses the fraction of        benzene converted to cumene+polyisopropylbenzenes with respect        to the total quantity of converted benzene.

EXAMPLE 6 Catalytic Test

A catalytic test is effected, using the same experimental apparatus andthe same experimental conditions as Example 5, but charging thecatalytic system prepared according to what is described in Example 2,in a quantity equal to 9 g, for a total height of the catalytic bedequal to 8.3 cm. The benzene is fed with a flow-rate equal to 0.184ml/min.

Approximately 3 hours after the start of the acetone feeding, samples ofreaction effluent are removed, both for the liquid and gaseous part,which are subsequently analyzed by gaschromatography.

Table 1 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 7 Catalytic Test

A catalytic test is effected, using the same experimental apparatus andthe same experimental conditions as Example 5, but charging thecatalytic system prepared according to what is described in Example 3,in a quantity equal to 11 g, for a total height of the catalytic bedequal to 8.5 cm. The benzene is fed with a flow-rate equal to 0.251ml/min.

Approximately 3 hours after the start of the acetone feeding, samples ofreaction effluent are removed, both for the liquid and gaseous part,which are subsequently analyzed by gaschromatography.

Table 1 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 8 Catalytic Test

A catalytic test is effected, using the same experimental apparatus andthe same experimental conditions as Example 5, but charging thecatalytic system prepared according to what is described in Example 3,in a quantity equal to 11 g, for a total height of the catalytic bedequal to 8.5 cm. The acetone is fed with a flow-rate equal to 0.009ml/min, the benzene with a flow-rate equal to 0.072 ml/min.

Approximately 3 hours after the start of the acetone feeding, samples ofreaction effluent are removed, both for the liquid and gaseous part,which are subsequently analyzed by gaschromatography.

Table 1 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 9 Catalytic Test

A catalytic test is effected, using the same experimental apparatus andthe same experimental conditions as Example 5, but charging thecatalytic system prepared according to what is described in Example 4,in a quantity equal to 5 g, for a total height of the catalytic bedequal to 5 cm.

The catalyst is then subjected to drying in a stream of nitrogen and thetemperature inside the reactor is brought from 120° C. to 190° C. inabout 2 hours. Once a constant temperature of 190° C. has been reached,the stream of nitrogen is then interrupted and the feeding of benzene isinitiated with a flow-rate equal to 0.254 ml/min. The system ismaintained under these conditions for 60 minutes, after which thefeeding of hydrogen is reactivated at a flow-rate equal to 27.3 ml/minand after a few minutes the feeding of acetone is initiated with aflow-rate equal to 0.036 ml/min.

Approximately 3 hours after the feeding of acetone, samples of reactioneffluent are removed, both for the liquid and gaseous part, which aresubsequently analyzed by gaschromatography. Table 1 summarizes theoperating conditions, together with the results obtained.

TABLE 1 Example Nr. 5 6 7 8 9 Quantity of catalytic system (g) 14.5 9 1111 5 Reaction temperature (° C.) 150 150 150 150 190 Reaction pressure(kpa) 100 100 100 100 100 Total WHSV (h⁻¹) 0.9 1.1 1.2 0.4 3.0[Benz.]/[Acetone] molar ratio 16.8 12.6 17.2 6.3 5.8 [H₂]/[Acetone]molar ratio 7.4 7.4 7.4 9.77 2.5 Conversion of acetone % 100.0 100 100100 98.5 [aryls]/[acetone] selectivity % 96.6 88.3 94.6 98.0 89.1[cumene]/[acetone] selectivity % 81.9 70.2 79.8 79.7 81.0[aryls]/[benzene] selectivity % 99.4 96.7 99.0 99.8 96.7

EXAMPLE 10 Preparation of the Catalytic System

A material is prepared, consisting of a catalyst based on copperaluminate (produced by SüdChemie under the trade-name of T4489,indicated hereunder as “material A2”, having the following compositionexpressed as weight percentage of the elements: Cu 39.3%, Al 15.5%, Zn6.0%, Mn 6.8%), zeolite beta and alumina p-bohemite. The zeolite betaand alumina are the same materials used in the previous examples.

173 g of alumina, 192 g of zeolite beta, 124 g of T4489 are charged intoa ploughshare mixer and mechanically mixed for about 60 minutes, afterwhich 400 cc of an aqueous solution of acetic acid at 2% w/w are addedto the mixture of powders thus obtained, without interrupting the mixingfor a further 60 minutes approximately.

The intermediate thus obtained is then subjected to extrusion using aHUTT type gear press extruder and the product obtained is then subjectedto aging for a period of not less than 48 hours.

After the aging period, the product, in the form of pellets, issubsequently subjected to calcination treatment in air at a temperatureof about 550° C. for 5 hours, obtaining a material called “material B3”,containing about 30% of copper aluminate T4489, about 40% of zeolitebeta and about 30% of an alumina binding carrier. The catalytic systemis prepared so that it consists of two distinct zones, the firstcontaining 3 g of the material A2 and the second 7 g of the material B3prepared as described. The total quantity of catalytic system istherefore equal to 10 g.

EXAMPLE 11 Preparation of the Catalytic System

A material consisting of copper aluminate T4489 and zeolite beta,already used in the previous example, is prepared.

298 g of zeolite beta, 255 g of T4489 are charged into a ploughsharemixer and mechanically mixed for about 60 minutes, after which 365 cc ofan aqueous solution of acetic acid at 5% w/w are added to the mixture ofpowders thus obtained, without interrupting the mixing for a further 60minutes approximately.

The intermediate thus obtained is then subjected to extrusion using aHUTT type gear press extruder and the product obtained is then subjectedto aging for a period of not less than 48 hours.

After the aging period, the product, in the form of pellets, issubsequently subjected to calcination treatment in air at a temperatureof about 550° C. for 5 hours, obtaining a material called “material B4”,containing about 50% of copper aluminate T4489 and about 50% of zeolitebeta. The catalytic system is prepared so that it consists of twodistinct zones, the first containing 3 g of the material A2 and thesecond 7 g of the material B4 prepared as described. The total quantityof catalytic system is therefore equal to 10 g.

EXAMPLE 12 Catalytic Test

A catalytic test is carried out, using the same experimental apparatusdescribed in Example 5.

The catalytic system prepared as described in Example 10 is charged intothe reactor in a quantity equal to 10 g, with a size ranging from 1 to 2mm, for a total height of the catalytic bed equal to 8.5 cm.

A quantity of inert quartz material is charged over and under thecatalytic bed for a height equal to 2 cm over and 2 cm under thecatalytic bed.

The catalyst is then subjected to drying in a stream of nitrogen for 1hour during which the internal temperature is brought to 210° C. Oncethis temperature has been reached, a stream of 1.3 ml/min of benzene isfed for about 30 minutes. The temperature is then lowered to 194° C.,the pressure is brought to 2100 Kpa and the nitrogen flow isinterrupted. A stream of 367 ml/min of hydrogen is subsequently fed forabout 30 minutes. Finally, the benzene feeding is interrupted and a flowof 0.77 g/min of a benzene and acetone solution [C6]/[C3]=6.3, is fed.

About 3 hours after the start of the acetone feeding, samples ofeffluent are taken from the reaction, both for the liquid and gaseouspart, which are subsequently analyzed by means of gaschromatography.Approximately 24 hours after the start of the feeding, the samplingoperation is repeated with the same analysis procedure.

Table 2 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 13 Catalytic Test

A catalytic test is carried out, using the same experimental apparatusdescribed in Example 5 and under the same experimental conditions asExample 12. The catalytic system prepared as described in Example 11 ischarged into the reactor in a quantity equal to 10 g, with a sizeranging from 1 to 2 mm, for a total height of the catalytic bed equal to8.1 cm.

About 3 hours after the start of the acetone feeding, samples ofeffluent are taken from the reaction, both for the liquid and gaseouspart, which are subsequently analyzed by means of gaschromatography.Approximately 24 hours after the start of the feeding, the samplingoperation is repeated with the same analysis procedure.

Table 2 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 14 Catalytic Test

A catalytic test is carried out, using the same experimental apparatusdescribed in Example 5 and under the same experimental conditions asExample 12, but charging the catalytic system prepared as described inExample 3 in a quantity equal to 11 g for a total height of thecatalytic bed equal to 8.3 cm. A flow of 0.76 g/min of a solution ofbenzene and acetone [C6]/[C3]=6.3, is fed.

About 3 hours after the start of the acetone feeding, samples ofeffluent are taken from the reaction, both for the liquid and gaseouspart, which are subsequently analyzed by means of gaschromatography.Approximately 24, 173 and 384 hours after the start of the feeding, thesampling operation is repeated with the same analysis procedure.

Table 2 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 15 Catalytic Test

A catalytic test is carried out, using the same experimental apparatusdescribed in Example 5, but charging the catalytic system prepared asdescribed in Example 3 in a quantity equal to 11 g for a total height ofthe catalytic bed equal to 8.4 cm.

The catalyst is subjected to drying in a stream of nitrogen at atemperature inside the reactor equal to 160° C. for about 1 hour, afterwhich a flow of 5.2 ml/min of hydrogen is fed at low pressure for 60minutes, followed by a flow of 15.8 ml/min at 180° C. for 120 minutesand finally a flow of 23.6 nl/min at 200° C. for 180 minutes. Thehydrogen feeding is then interrupted and the temperature of the reactoris brought to a value equal to 170° C., the experimental apparatus beingmaintained in a stream of nitrogen.

Once the temperature has reached a constant value of 170° C., thenitrogen stream is interrupted and the feeding of benzene is initiatedwith a flow-rate equal to 0.36 ml/min. The pressure is brought to 850Kpa.

The system is maintained under these conditions for 60 minutes, afterwhich the feeding of hydrogen is restarted at a flow-rate equal to 338ml/min; after a few minutes, the benzene feeding is interrupted and aflow of 0.76 g/min of a solution of benzene and acetone [C6]/[C3]=6.3,is fed.

About 3 hours after the start of the acetone feeding, samples ofeffluent are taken from the reaction, both for the liquid and gaseouspart, which are subsequently analyzed by means of gaschromatography.

Table 2 summarizes the operating conditions, together with the resultsobtained.

EXAMPLE 16 Catalytic Test

A catalytic test is carried out, using the same experimental apparatusdescribed in Example 5, but charging the catalytic system prepared asdescribed in Example 3 in a quantity equal to 11 g for a total height ofthe catalytic bed equal to 8.4 cm.

The catalyst is subjected to drying in a stream of nitrogen for 1 hourduring which the temperature inside the reactor is brought to 230° C.Once this temperature has been reached, a flow of 1.3 ml/min of benzeneis fed for about 30 minutes. The temperature is then lowered to 210° C.,the pressure is brought to 2900 Kpa, the nitrogen stream is interruptedand a flow of 367 ml/min of hydrogen is fed for about 30 minutes.Finally, the benzene feeding is interrupted and a flow of 0.76 g/min ofa solution of benzene and acetone [C6]/[C3]=6.3, is fed.

About 20 hours after the start of the acetone feeding, samples ofeffluent are taken from the reaction, both for the liquid and gaseouspart, which are subsequently analyzed by means of gaschromatography.

Table 2 summarizes the operating conditions, together with the resultsobtained.

TABLE 2 Example Nr. 12 13 14 15 16 Time of stream (h) 3 24 3 24 3 24 173384 3 24 20 Quantity of catalytic system (g) 10 10 10 10 11 11 11 11 1111 11 Reaction temperature (° C.) 194 194 194 194 194 194 194 194 174174 210 Reaction pressure (kpa) 2100 2100 2100 2100 2100 2100 2100 2100850 850 2900 Total WHSV (h⁻¹) 4.6 4.6 4.6 4.6 4.1 4.1 4.1 4.1 4.1 4.14.1 [Benz.]/[Acetone] molar ratio 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.36.3 6.3 [H₂]/[Acetone] molar ratio 11.9 11.9 11.9 11.9 11.9 11.9 11.911.9 10.8 10.8 11.9 Conversion of acetone (%) 100.0 100.0 100.0 100.0100.0 100.0 100.0 100.0 100.0 100.0 100.0 [Aryls]/[Acetone] selectivity(%) 97.8 97.8 97.6 97.8 97.7 97.8 97.7 97.0 97.1 96.2 96.9[Cumene]/[Acetone] selectivity (%) 76.6 76.7 73.9 73.7 76.9 77.0 76.876.2 68.7 70.1 83.8 [Aryls]/[Benzene] selectivity (%) 98.8 99.0 98.798.8 99.2 99.3 99.3 99.1 99.6 99.3 99.2

1. A catalytic composition, comprising: a zeolite in acid form, Cu andone or more elements selected from the group consisting of an element ofGroup IIIA, an element of Group IVA, an element of Group IIIB, anelement of Group IVB, an element of Group VB, an element of Group VIB,an element of Group VIIB, Fe, Ru, Os, and an element of the lanthanideseries; wherein when the element is chromium, copper and chromium are atleast in part in the form of copper chromite and when the element isaluminum, copper and aluminum are at least in part in the form of copperaluminate.
 2. The catalytic composition according to claim 1,comprising: a zeolite in acid form, Cu and one or more elements selectedfrom Al and Cr, wherein when the element is chromium, copper andchromium are at least in part in the form of copper chromite and whenthe element is aluminum, copper and aluminum are at least in the form ofcopper aluminate.
 3. The catalytic composition according to claim 1,comprising a zeolite in acid form, selected among zeolite beta, zeoliteZSM-12 and mordenite; Cu and one or more elements selected from thegroup consisting of an element of Group IIIA, an element of Group IVA,an element of Group IIIB, an element of Group IVB, an element of GroupVB, an element of Group VIB, an element of Group VIIB, Fe, Ru, Os, andan element of the lanthanide series.
 4. The catalytic compositionaccording to claim 1, comprising zeolite Y in acid form, Cu, and one ormore elements selected from the group consisting of an element of GroupIIIA, an element of Group IVA, an element of Group IIIB, an element ofGroup IVB, an element of Group VB, an element of Group VIIB, Fe, Ru, Os,and an element of the lanthanide series.
 5. The catalytic compositionaccording to claim 1, further comprising a binder.
 6. The catalyticcomposition according to claim 1, wherein the zeolite is zeolite beta.7. A process for preparing the catalytic composition according to claim1, comprising impregnating the zeolite with an aqueous solutioncontaining a copper salt and a salt of one or more elements selectedfrom the group consisting of an element of Group IIIA, an element ofGroup IVA, an element of Group IIIB, an element of Group IVB, an elementof Group VB, an element of Group VIB, an element of Group VIIB, Fe, Ru,Os, and an element of the lanthanide series, to form a product, anddrying and calcining the product.
 8. The process according to claim 7,wherein the resulting product is bound with an inorganic binder.
 9. Aprocess for preparing the catalytic composition according to claim 1,comprising impregnating the zeolite and one or more inorganic binderswith an aqueous solution containing a copper salt and a salt of one ormore elements selected from the group consisting of an element of GroupIIIA, an element of Group IVA, an element of Group IIIB, an element ofGroup IVB, an element of Group VB, an element of Group VIB, an elementof Group VIIB, Fe, Ru, Os, and an element of the lanthanide series, toform a product, and drying and calcining the product.
 10. A process forpreparing the catalytic composition according to claim 1, comprisingperforming an ionic exchange of the zeolite with an aqueous solutioncontaining a copper salt and a salt of one or more elements selectedfrom the group consisting of an element of Group IIIA, an element ofGroup IVA, an element of Group IIIB, an element of Group IVB, an elementof Group VB, an element of Group VIB, an element of Group VIIB, Fe, Ru,Os, and an element of the lanthanide series, and drying and calciningthe product.
 11. The process for preparing the catalytic compositionaccording to claim 10, wherein the product obtained is bound with abinder.
 12. A process for preparing the catalytic composition accordingto claim 1, comprising performing an ionic exchange of a composition ofzeolite and suitable binding agents with an aqueous solution containinga copper salt and a salt of one or more elements selected from the groupconsisting of an element of Group IIIA, an element of Group IVA, anelement of Group IIIB, , an element of Group IVB, an element of GroupVB, an element of Group VIB, an element of Group VIIB, Fe, Ru, Os, andan element of the lanthanide series, to form a product, and drying andcalcining the product.
 13. A process for preparing the catalyticcomposition according to claim 1, comprising extruding, drying andcalcining a mechanical mixture, paste-mixed with a peptizing agent, ofthe zeolite, Cu, and one or more elements selected from the groupconsisting of an element of Group IIIA, an element of Group IVA, anelement of Group IIIB, an element of Group IVB, an element of Group VB,an element of Group VIB, an element of Group VIIB, Fe, Ru, Os, and anelement of the lanthanide series, in the form of oxides.
 14. A processfor preparing the catalytic composition according to claim 1, comprisingextruding, drying and calcining a mechanical mixture, paste-mixed with apeptizing agent, of the zeolite, Cu, and one or more elements selectedfrom the group consisting of an element of Group IIIA, an element ofGroup IVA, an element of Group IIIB, an element of Group IVB, an elementof Group VB, an element of Group VIB, an element of Group VIIB, Fe, Ru,Os, and an element of the lanthanide series, in the form of oxides, andone or more inorganic binders.
 15. A process for preparing the catalyticcomposition according to claim 1, comprising assembling various distinctzones, each comprising a metallic component, or a zeolitic component, ora combination of both components, and wherein the metallic componentcomprises copper and one or more elements selected from the groupconsisting of an element of Group IIIA, an element of Group IVA, anelement of Group IIIB, an element of Group IVB, an element of Group VB,an element of Group VIB, an element of Group VIIB, Fe, Ru, Os, and anelement of the lanthanide series.
 16. A catalytic composition,comprising: a zeolite in acid form; copper; one or more elementsselected from the group consisting of an element of Group IIIA, anelement of Group IVA, an element of Group IIIB, an element of Group IVB,an element of Group VB, an element of Group VIB, an element of GroupVIIIB, Fe, Ru, Os, and an element of the lanthanide series; andchromium; wherein at least a portion of the copper and the chromium arepresent in the form of copper chromite.
 17. A catalytic composition,comprising: a zeolite in acid form; copper; one or more elementsselected from the group consisting of an element of Group IIIA, anelement of Group IVA, an element of Group IIIB, an element of Group IVB,an element of Group VB, an element of Group VIB, an element of GroupVIIB, Fe, Ru, Os, and an element of the lanthanide series; and aluminum;wherein at least a portion of the copper and the aluminum are in theform of a copper aluminate.